The present invention generally relates to an atomic absorption spectrometer having a chamber through which passes a measuring beam and in which an atomization means is disposed and, in particular, relates to such a chamber wherein the atomization means provided is selectable.
Conventionally, an atomic spectrometer is used to determine the concentration of an element being sought in a sample. For this purpose, an atomization means is provided for producing an "atom cloud" in which the constituents of the sample are present in an atomic state. A measuring beam, having a light spectrum the same as the absorption spectrum of the element being sought, is directed through the atom cloud and the absorption thereof in the atom cloud is measured. The amount of absorption is representative of the concentration of the element being sought in the sample.
Various atomization means, i.e. means which convert the sample into an atomic condition, are known for such purposes. One such atomization means is a burner wherein the sample is sprayed into the fuel gas-air mixture thereof. The constituents of the sample are decomposed in the flame so that the elements are present in atomic form in the flame.
Another technique employed in atomic absorption spectroscopy is generally known as "flameless atomic absorption spectroscopy". An example of an atomization means for flameless atomic absorption spectroscopy is the conventional graphite tube cell. As well dnown, a graphite tube cell includes a graphite tube positioned between a pair of electrodes. After a sample is introduced into the graphite tube an electrical current is passed, via the electrodes, through the graphite tube so that the graphite tube is heated to high temperatures. In various steps, the sample is dryed, incinerated, and finally atomized, thus forming the "atom cloud" within the graphite tube. In this technique the measuring beam is directed in the longitudinal direction through the graphite tube and the associated annular electrodes. An example of a graphite tube cell of this kind is described in U.S. Pat. No. 4,176,956.
Additionally, it is known that for hydride-forming elements in the sample to be made available to atomic absorption measurement suitable reagents are added to a sample fluid. As a result, a volatile hydride of the element being sought is formed and driven out of the sample. The volatile hydride is then conveyed, usually via a protective carrier gas, into a heated measuring cuvette in which the hydride is decomposed, This decomposition causes the element being sought to be converted in the measuring cuvette into its atomic state, i.e. in the form of an atom cloud through which the measuring beam passes. Examples of such means for the formation of a hydride are described in U.S. Pat. No. 4,183,215 and U.S. Pat. No. 4,208,372.
In any event, substituting one type of atomization means for another is a complicated procedure. For example, the atomization means must be installed and adjusted. In addition, connectors for the supply of current and/or cooling fluid and/or protective gas must also be installed. Generally, the time required for such conversion operations is often relatively long if samples are to be investigated by different methods.